Process of synthesizing lead tetra-alkyis



Patented Aug. 25, 1925.-

UNITED STATES v 4 1,550,940 PA Kr wrnmams or cAnNEYs POINT, AND HERBERT w. naun'r, or PENNS enov'n, NEW

TENT OFFICE.

V JERSEY, assIoNons TO B. I; DU POINT DE'NEMOUBS & COMPANY, 01 WILMINGTON,

.DELAWARE, A conrone'rrouor DELAWAIRIL 1T0 Drawing.

To all whom; it may concern:

Be it known that we, KI WILLIAMS, a.

citizen of the United States, and a resident vented a'certain new and useful Process of Synthesizing Lead Tetra-Alkyls, of which the following is a specification.

This invention relates to the production of lead tetra-alkyls by the interaction of metallic lead and an alkyl bromide in the presence of a; reducing agent and of a catalyst, and comprises mixing a solutionof a strong base-for example, an alkali-metal hydroxide -with the reaction mass resulting from said interaction, and then proceeding in the usual way to remove excess allryl bromide and distill off the tetra-alkyl lead. By this intermediate addition of'a strong alkali. the yield of tetra-alkyl lead is substantially increased. v

Alkaline-solutions of the kind indicated above can be used-to advantage in the treatment of reaction masses obtained in various ways from lead and an alkyl bromide Thus, reaction masses to which the aforesaid souti'onsmay advantageously be added may be produced in accordance with processes described in co-pendin'g applications of William S. Caloott, Ser. No.- 592,598, filed October 5, 1922; VVillianrS. Calcott and H. W.

Daudt, Ser. No. 594,583,'fi1ed October 14, 192% and 11 P. Monroe, Ser. Nos. 596,514; 707,581, and 729,046, April 19, 1924an'd July 30, 1924, respectively. The increased yield resulting from the abo've-described treatment is believed to be due to the presence, in the reaction mixtures above referred to. of a.si1.bst-antial proporti'on ,of hexja-alkyl-di plumbane (Pb -klk which is converted bythis special treatment into a tetra-all yl lead. The conversion of other intermediate products to tetra-ethyl lead and the disintegration of the sludge may also contribute to the increase in yield. The latter factor also allows an easy trans-' fer of the reaction mass from one piece of equipment to another.

Our new process may following example:

be illustrated by the "finally tetra-ethyl lead. v Instead of sodium hydroxide, potassiumtill ofl first excessalkvl bromide and then filed October 23, 19522,

- PROCESS OF SYNTHESIZINGVLEAD TETRA-ALLYIS.

Application filed August 9, 1924. Serial No. 731,060.

100 parts of lead-sodium alloy containing 14.3% sodium, 85 parts of ethyl bromide, 8 parts of ethyl cyanide, 0.4 parts of water; and 2 parts of pyridine are placed in a steel tube which is then closed and rotated for about 8 hours in an oil bath maintained at 83-85 C. The tube is then opened and to the reaction mass therein, there are added 115 parts of 6% sodium hydroxide solutionthe sodium hydroxide solution being equal in weight to eight times the active so-- dium contained in the alloy used. The resulting mixture is digested at a temperature of 50 C. for 5 hours, and then heated to distill off first excess ethyl bromide and hydroxide may be used in the above example. g

We claim: l

1. In the process of producing lead tetraalky'ls by the interaction of lead andan -,all yl bromide in the presence of a reducing agent and a catalyst, the step which cornprises mixing with the reaction mass resulting from said interaction, a.solut1on of a strong. base. I

2. A process. as set forth 1n claim I m whicl'i. after mixing the. reaction mass Wltll the-solution of a strong base; the resu ting mixture is digested and then heated to distetra-alkyl lead.

3. In the process of producing tetra'ethyl lead bythe interaction "of a leadsodium alloy having approximatelythe composition indicated bythe formula PbNa withethyl bromide and a neutral hydroxylic compound capable of reacting with sodium to form hydrogen, in the presence'ofa catalyst, the step which comprises mixing water and an alkali-metal hydroxide w th the reaction.

mass resulting from said interaction.

4. A process as defined in claim 3 m wh ch the mixture obtained by mixing water and an alkali with the reaction mass is digested -for about 5 hours at a temperature of about 50 (3., and subjected to distillation to drive ofii' first ethyl bromide and then tetra-ethyl hydroxide is sodium hy- 1 1 s. A process as defined in c1aim1inwl ai :h about eoual in weight to eight times the the solution of a strong base. is a 6% sodmm HCtITGYSOdi um contained in the alloy usd. v

hel eof we afiix our signahydroxide solutiom v I 5 which the water and alkali-metal hydroxide are so proportioned as to form a. 6% solui tion, and the amount of such solution used is o y In testimony w 7. A process as defined in' claim 3 in tures.

KI WILLIAMS. 

